=> Rename the variable to LC_SSH_USER and you have no problems… AND… it’s accepted by package default:

# grep LC /etc/ssh/sshd_config
AcceptEnv LANG LC_*

Bests 😉

/etc/profile.d/ssh.csh:
if [ „$SSH_USER“ != „“ ]; then
logger -ip auth.notice -t sshd „Accepted publickey for $SSH_USER“
setenv HISTFILE „$HOME/.history_$SSH_USER“
fi

/etc/profile.d/ssh.sh:
if [ „$SSH_USER“ != „“ ]; then
logger -ip auth.notice -t sshd „Accepted publickey for $SSH_USER“
export HISTFILE=“$HOME/.bash_history_$SSH_USER“
fi

Bests

^ is this not a massive security risk.

Enabling environment processing may enable users to
bypass access restrictions in some configurations using
mechanisms such as LD_PRELOAD.

I’m wondering to know where you put your small script for the logging ?

Is it in the /etc/profile ? /etc/ssh/sshrc, or another place ?

Thanks